Apparatus for crystallization of sugar bearing materials



c. HASTINGS 2,743,197

APPARATUS FOR CRYSTALLIZATION OF SUGAR BEARING MATERIALS April 24, 1956 Filed June 1'7, 1954 F INVENTOR Courf/anc/ Has/7 BY MS af/omeys United States APPARATUS FOR CRYSTALLIZATION OF SUGAR h BEARING MATERIALS Courtland Hastings, New York, Y. Application June 17,1954, Serial'No.-'437,529 v i j 11 Claims. Cl. 127-15 final stage of crystal development for the purpose of accelerating the abstraction of sugar from. the surrounding mother liquor by causing it t to deposit uniformly on already established crystals and to increase the total yield of sugar. I

The invention is useful in connectionwith and is adapted to existing crystallizers of'conventionaltype as well as being useful in new installations. p I g In existing crystallizers, the'container or tank is usually of elongated U-shape in cross section and is open at the top. The conventional units are generally equipped with radial stirring devices which are rotated slowly. They are also quite generally equipped with coolingcoils which are of many different-types. Indescribingtheinvention and in putting it to use, it will be assumed-that the stirring devices and cooling coils can continue to be used, with some rearrangement in position, in combination with the invention. 1

It is an object of the invention to improve the structure and operation of the existing conventional type to enable them to be used in a process which is continuous in operation andprovides for movement of the sugar bearing material continuously from the inlet to the outlet.

Another object is to provide for conversion of existing crystallizer units from batch to continuous processing by crystallizers, which ordinarily function as batch units, H

along line x-x of Fig. 2.

, 2,743,197 Patented Apr. 24, 1956 total time required for attainment of maximum crystallization is shortened. I

Achievement of the foregoing objectives and benefits of the invention provides for moreefiective working-out or crystallization, or in other words, a higher degree of crystallization than is possible with usual crystallizers, while at the same time maintaining a somewhat lower density of massecuite than. would otherwise be necessary.

The accomplishment of these and the other objectives of the invention is reflected in considerable economic gain by reason of the amount of crystallization attainable with the volume of crystallizer capacity available, thus affecting the total commercial sugar output from the raw material. This affects the earnings and the unit'production cost of the sugar producer and refiner;

Other objects and advantages of my'invention 'will become apparent as it is described in connection with the accompanying drawing. i

In the drawing: 1

Fig. l is an end elevation view partly ,in section :of apparatus embodying the invention. The section is taken Fig. 2 is a plan View of, the twolower tanks of Fig. 1 of that apparatus and diagrammatically illustrating the flow of the material through the apparatus.

r I Referring to the drawing, an elongated supply tank 10 receives themassecuite or other sugar bearing materials discharged from vacuum pans or the like (not shown) in which theboiling under vacuum hasbeen 'carriedout to a point to render the material of suitable .density.

During this boiling process, the sugar crystals have been established and developed to'a considerable degree, but require further development. I

: :Beneath the supply tank 10 is locateda crystallizer tank 20 which, for the purpose of illustration, is illustratedasof some convenient and' 'conventional length and generally of U-shape in cross section. Another similar tank 40 is located alongside of the crystallizer tank-20 with its axis parallel to the tank 20and in positionzto receive the material delivered from the tank 20, as will hereinaftermoreffully appear. Since two or more crystallizers have quite commonly hcretoforebeen'located in parallel arrangement in existing installations, the invention is applicable to many existing crystallizer tanks without the need to move these rather heavy and bulky pieces of apparatus andwithout the need for' full scale re-arrangement of the sugar house or refinery. It should be understood, however, the invention is not limited to parallel arrangement of tanks at the same level.

Material maybe deliveredthrougha conduit or" pipe 12-:from the bottom of the supply tank'into the topof thecrystallizer 20. Preferably the'delivery will beat the central zone of the crystallizers by providing means for more thorough displacement of the massecuite and to better control the flow in order to have a more uniform final product than is possible-in conventional crystallizers.

A related object is to provide means for more'thorough displacement, in order to overcome 'anytendency of the crystals to develop diiferently in different longitudinal zones in close proximity to the travel ofthe stirrers or to the cooling coils, byproviding means for forcing the material in the course of its movement from the periphthe same time by varying rates of movement, whereby the rate of crystal development is accelerated and" the a mid-point in the tank'at the location 14 in-. Fig." 2. Since it is desirable'to have the inflow of material from the supply tank at a regulated rate, a control valve 16 may be supplied for that purpose in the discharge conduit 12. p The adjacentcrystallizer tanks are identical and, hence 'a'description' of one willsufiice.

In order to stir and distribute the material, rotary stirring devices are located the tank, mounted upon a longitudinally extending shaft 22 'supportedin bearings 24 in the end walls of the tank, As illustrated there are seven stirring devices AG in each tank, but obviously the number depends upon the length of the tank, thelocation of the cooling coils, if such are used, and the nature of the most diflicult material which it is expected the apparatus will be expected to handle, as well as upon other factors. f U

The stirrers may comprise-paddles or bladesf26 extending from the shaft 20 in substantially radial planes and may be of any suitable shape. In the form illustrated,

the stirring arms are right-angular in cross section and are bolted together on opposite sides of the shaft and extend in opposite directions. The .arms of adjacent stirring devices may be angularly spaced by 90, if desired to improve the stirring action along-the tank.

The stirring devices are rotated slowly with the shaft 22 by a gear 28 on the outside end of the shaft 22 through motor driven reduction gearing 29.

In order to maintain a system of circulation independent of the slow movement of the material from the inlet 14 toward the outlet points and to subject a portion of the massecuite -'in each tank to a substantially accelerated movement which will force the crystals into fresh exposure with the surrounding supersaturated liquor, or both, supplemental stirring and mixing means is pro- -vided. This means comprises .L-shaped hollow tubes 80, 30', the upper ends of which are near the surface of the material being stirred within the tank, while the lower ends are nearer the bottom of the tank at a position almost diametrically opposite the upper ends. In the upper ends a rotating screw impeller 34 is inserted. The impeller is mounted upon a-vertical shaft extending above the top of the tank and is driven by a-motor 36 through a reduction gear 37 of any suitable and conventional type. As illustrated, the motor is mounted'with its vertical shaft, but it will be obvious that the motor could be mounted with its shaft horizontal and could work throughreduc'tion gearing upon the shaft of the impeller. As illustrated, thereare two such impeller tubes (30, 30') which are located betweenthe second and third stirring .devices from each end of the crystallizer tank. Obviously, @however, additional impeller tubes could be incorporated .along the length of the tank as varying conditions might require.

It will be apparent that material taken in through the .:top of the impellertube will be forced by the screweonveyor 34 into and through the tube and out the lower end. The force exerted by the screw conveyor upon this material may .be considerable to afford a much greater :acceleration .and velocity of the material than is :maintained by the surrounding material outside the tube. Thus, frictional contact and rubbing of the crystals are attained within the impeller tube and additional :force is imparted as the material .is forcedout .of the tube. This all creates a new and different condition of the stirred material within the tank, giving rise ;to.greater crystallization and exhaustion of the sugar from thematerial.

As may be observed from the directional arrows shown in dotted lines, the material taken in at the top of the. im peller tube passes through the tube as it leaves the lower end, mushrooms out and comes into the zone of influence of the stirring devices .on each side thereof, which tends to cause the material expelled from the end of the tube to mix in with the surrounding material. The admixture will beswept upwardly by the stirring devices. It is thus taken around into the area wherein it, or at leasta portion thereof,.;may be drawn in through the top of the tube and L mixed with material inganother part of the tank.

However, the continuous delivery into the crystallizer .thfmlgh the inlet pipe 12 tends to force the material as it is mixed and processed to move towards the ends ofthe tank from the middle thereof, as is illustrated by the arrows shown in solid lines. As the processed material reaches the .ends of the tank, it is given a final stirring and tends to rise slightly on :one side (the left side) :as viewed in Fig. l. i

In order to discharge the-material fromone crystallizer wherein the processing has been partially completedand to deliver that material to the next adjacent crystallizer, a trough 38-is formed longitudinally of the tank adjacent one side near the upper edge thereof but below the top surface of thecrystallizer tank wall. This trough may be of substantially U-shape. The tank wall constitutes one side of the trough and thebottomand othersidfi may be formedof sheet-metal or other suitable material-welded to or otherwise su ta y suppo ted from the side .of th tank wall inside the tank. The ends of the trough are -opon-to permitthe treated materialto enter the ends and to move along the trough. The inside wall of the trough, being solid imperforate, prevents movement of material into it from the inlet 12 before adequate processing.

At the center of the trough in the sidewall of the tank, there is provided an outlet duct or trough 39 which is connected with the adjacent crystallizer tank at its top in .order to deliver the material to the next tank 40 for processing therein. Material entering tank 40 from duct 39 is treated in the same manner and by the same mechanism and means as in tank 20. When processed in tank 40,'th e materialmaythen flow outthrough exit duct 39 to another crystallizer or other apparatus.

As the material passes from one tank to another, it is progressively treated and the sugar exhausted to the fullest extent by crystallization in a manner which is more effective than the conventional crystallization methods.

From the foregoing, the operation of the apparatus and method of treatment may be understood.

Three influences are present tending to move the material in three paths which intersect and cooperate to provide a new and effective stirring for more efficient crystallization. :(a) The general movement of the material is from the inlet point to the outlet trough and duct. (11) A circular stirring action is imparted by the radial stirring devices. (0) A cross current circulation causes diametrical displacement of small portions of the material regularly. I

Recognizing'that the material undergoing treatment has a'highuviscosity, itwill be appreciated that the stirring arms exert a considerable dragging effect upon the material. This slowly movesthe material from the bottom of the cell to the-top and vice versa. By taking relatively small portions o'fthe total volume of the material by the screw impeller and moving said portions from one side of the tank to the other in a shortened path, with acceleration -if desired, a complete displacement of the entire volume of the crystallizer may be accomplished as the material moves from inlet to exit point.

Many existing crystallizers are equipped with cooling coils, such as described and illustrated in the Kopke Patent 1,749,588. These' coils can be incorporated or can -be maintained with .good effect, while utilizing the pres- .ent invention since they do not interfere with the functioning or-principles of the invention, but rather combine and coordinate therewith. They contribute towards accele'ration of crystallization by increasing the degree of supersaturation of the material as they lower the temperature of "the mixture.

Modifications within the scope of the invention will occur-to those skilled in the art. Therefore, the invention is not limited to the specific form shown and described.

'What is claimed is:

1. Apparatus for the continuous crystallization of sugar bearing material comprising a tank, stirring means within the tank operating in a predetermined orbit to stir the material, and means in the tank-taking portions of the material adjacent one point in said orbit and forcibly conducting the same through the tank in an isolated path shorter-than said orbitand delivering it adjacent an opposite point -in said orbit to cause intermingling of remote portions during the stirring.

2. Apparatus for the continuous crystallization of sugar bearing-material comprising atank, stirring means within the tank operating in a predetermined orbit to stir the material, conducting means in the tank for conducting portions of the material adjacent one point in said orbit and conducting the same through an isolated path inside the tank and delivering it adjacentan opposite point in said orbit tocause intermingling of remote portions during the stirring, and means in said conducting means to agitate the material and to force it through said conducting m ans.

3. Apparatus for the continuous crystallization of sugar bearing material comprising a tank, stirring means within the tank operating in a predetermined orbit to stir the material, conducting means in the tank for conducting portions of the material adjacent one point in said orbit and conducting the same through an isolated path shorter than said orbit and delivering it adjacent an opposite point in said orbit to cause intermingling of remote portions during the stirring, and a screw conveyor in said conducting means to agitate and to force the material through said conducting means.

4. Apparatus for the continuous crystallization of sugar bearing material comprising a tank, stirring means within the tank operating at positions along the tank in predetermined orbits to stir the material, and a plurality of conducting means in the tank located at, spaced points along the tank, each taking portions of the material adjacent one point in an orbit and delivering it adjacent an opposite point, and means to force said portions through the conducting means to cause intermingling of remote portions during stirring.

5. Apparatus for the continuous crystallization of sugar bearing material comprising a tank, stirring means within the tank operating in predetermined orbits to stir the material, and a plurality of conducting means in the tank located at spaced positions along the tank, each taking portions of the material adjacent one point in an orbit and delivering it adjacent an opposite point to cause intermingling of remote portions during stirring, and a screw conveyor in said conducting means to agitate and to force the material through said conducting means.

6. Apparatus as claimed in claim 1 having means to continuously introduce material at one point in the tank, and means to take processed material at a point remote from the introduction point.

7. Apparatus as claimed in claim 1 having means to continuously introduce material midway along the tank,

and conducting means running along the tank admitting processed material only at its ends from the ends of the tank, and a discharge passage from the central portion of said conducting means to deliver processed material continuously from said apparatus.

8. Apparatus for the continuous crystallization of sugar bearing materials comprising a tank, means to continuously deliver material to said tank, and means to continuously discharge processed material from the tank at a point remote from the delivery point, means to stir material in the tank in a path crosswise to the movement from inlet to outlet, and means in the tank to forcibly conduct portions of the material through an isolated path from one point adjacent the orbit of said crosswise stirring to an opposite point in the tank, said isolated path being shorter than the peripheral distance between said points.

9. Apparatus for the continuous crystallization of sugar bearing materials comprising a tank, means to continuously deliver material to said tank, and means to continuously discharge processed material from the tank at a point remote from the delivery point, means to stir material in the tank in a plurality of paths crosswise to the movement from inlet to outlet, in some crosswise paths the movement of said material toward the outlet being in the opposite direction to that in others, and means in the tank to forcibly conduct portions of the material through an isolated path from one point adjacent the orbit of said crosswise stirring and to an opposite point in the tank at a plurality of positions along the tank.

10. Apparatus for the continuous crysallization of sugar bearing materials compriisng a battery of crystallizer tanks, means to deliver material into the first tank at a regulated rate, each tank having an outlet passage, the outlet passage of one tank delivering to the succeeding tank, the inflow to each tank being at a point remote from the outflow, each tank having means to stir material in the tank in a path crosswise to the movement from inlet to outlet, and means in the tank to conduct portions of the material forcibly through an isolated path from one point adjacent the orbit of said crosswise stirring and to an opposite point in the tank, said isolated path being shorter than the peripheral distance between said points.

11. Apparatus for the continuous crystallization of sugar bearing materials comprising a tank, means to continuously deliver material to said tank, and means to continuously discharge processed material from the tank at a point remote from the delivery point, means to stir material in the tank in a path crosswise to the movement from inlet to outlet, and means in the tank to conduct portions of the material through an isolated path from one point adjacent the orbit of said crosswise stirring to an opposite point in the tank, and means to conduct the material at an accelerated rate through said isolated path.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Geerligs: Cane Sugar and its Mfg., London, 1924, p. 238.

Sugar Machinery, London, 1924, p. 245. 

1. APPARATUS FOR THE CONTINUOUS CRYSTALLIZATION OF SUGAR BEARING MATERIAL COMPRISING A TANK, STIRRING MEANS WITHIN THE TANK OPERATING IN A PREDETERMINED ORBIT TO STIR THE MATERIAL, AND MEANS IN THE TANK TAKING PORTIONS OF THE MATERIAL ADJACENT ONE POINT IN SAID ORBIT AND FORCIBLY CON- 